The Development of
Individual Differences in
Intelligence and Personality
University of Virginia
KinderCare Learning Centers, Inc., Montgomery, AL
A theory that explains becoming human, becoming a member of a culture and society, and becoming a unique human being must call on diverse theoretical resources in the biological and social sciences. To integrate such diverse concepts requires the umbrella of evolutionary theory, which alone can encompass so many levels of analysis ( Scarr, 1993). In this chapter, I present an elaboration of the theory of genotype → environment effects ( Scarr & McCartney, 1983) that was developed in my presidential address to the Society for Research in Child Development ( Scarr, 1992) and, further, in replies to critics of that article ( Scarr, 1993).
The major theses of the theory are: (a) an evolutionary perspective can unite the study of both species-typical development and individual variation; (b) environments within the normal species range are, of course, required for species-normal development, but research in modern societies suggests that individual variation among children reared in those environments arise primarily from genetic variation and from individually experienced environments, not from objectively measured environments; (c) environments should be seen as opportunities for experiences that are constructed by persons in developmentally changing and individually different ways; and (d) within dominant cultures in modern Western and Asian societies most differences in development are not due to differences in environmental opportunities.
Darwinian evolutionary theory has two simple principles: genetic variation and natural selection. Evolutionary theory's central principle is that gene